Now also labeled as a marine natural product, 53 reduced hypoxia-induced accumulation of HIF-1α protein with concentration dependency, with no effects upon the synthesis of cytoskeletal (tubulin) or cell cycle (cyclin D1) proteins in HeLa cells, inhibiting also tumor-conditioned media-induced angiogenesis via the diminished expression of VEGF [242]. This evidence concerns the gene HIF1A and neoplasm.